Revision 04bbc417cf2927b827660bc07743429783569aec authored by HwB on 10 February 2013, 00:00:00 UTC, committed by Gabor Csardi on 10 February 2013, 00:00:00 UTC
1 parent 0e3ae6b
gammainc.Rd
\name{gammainc}
\alias{gammainc}
\title{
Incomplete Gamma Function
}
\description{
Lower and upper incomplete gamma function.
}
\usage{
gammainc(x, a)
}
\arguments{
\item{x}{real number, not too big.}
\item{a}{real positive number.}
}
\details{
Computes the lower and upper incomplete gamma function, including the
regularized gamma function. The lower and upper incomplete gamma functions
are defined as
\deqn{\gamma(x, a) = \int_0^x e^{-t} \, t^{a-1} \, dt}
and
\deqn{\Gamma(x, a) = \int_x^{\infty} e^{-t} \, t^{a-1} \, dt}
while the regularized incomplete gamma function is
\eqn{\gamma(x, a)/\Gamma(a)}.
Accuracy is 7 significant digits along the real axis.
}
\value{
Returns a list with the values of the lower, the upper, and regularized
lower incomplete gamma function.
}
\references{
Zhang, Sh., and J. Jin (1996). Computation of Special Functions.
Wiley-Interscience, New York.
}
\note{
Directly converting Fortran code is often easier than translating Matlab
code generated with f2matlab.
}
\seealso{
\code{\link{gamma}}
}
\examples{
gammainc( 1.5, 2)
gammainc(-1.5, 2)
}
\keyword{ math }
Computing file changes ...